A List of Marine Reptiles: Ocean Animals Include Crocodiles, Iguanas, and Snakes

Learn about marine iguanas in the Galapagos, tropical venomous seas snakes, the deadly salt water crocodile, and endangered sea turtles.

Asked to imagine a reptile and most people will think of lizards sunning in the desert, snakes slithering through the jungle, or geckos skittering in the corners of a human home. However, many reptiles spend their days gliding through tropical waters and migrating throughout the world’s oceans. A list of marine reptiles includes crocodiles, iguanas, snakes, and turtles.

Sea Turtles Come in Many Sizes

Sea turtles are one of the oldest species still alive today with fossils dating back 150 million years – meaning sea turtles roamed the Earth along with dinosaurs. Today there are seven recognized species of sea turtle and the Caribbean Conservation Corporation describes each species in detail. These marine reptiles come in a variety of sizes with the olive ridley weighing less than 100 pounds and the leatherback reaching 1,300 pounds. Sea turtles can travel thousands of miles in a lifetime migrating from their feeding grounds to their nesting beaches. Unfortunately, all seven species of this marine reptile are now endangered due to human poaching, destruction of habitat, and pollution.

Marine Iguanas of the Galapagos

The marine iguana (Amblyrhyncus cristatus) is endemic to the Galapagos Islands off the coast of Ecuador. As the National Geographic describes in its “Marine Iguana Profile” scientists believe that land dwelling iguanas from South America floated on logs millions of years ago to the Galapagos. These scary looking herbivores can grow up to five feet long and use their sharp teeth to scrape algae off of rocks. Cornell University describes in “Marine Iguanas” how these creatures can dive for an hour at a time although they usually remain submerged for 5 to 10 minutes. Unfortunately, human-introduced predators such as rats and dogs are threatening these fascinating creatures. The marine iguana is considered vulnerable to extinction.

Sea Snakes are a Highly Poisonous Marine Reptile

Sea snakes can be found throughout the tropical waters of the world from Africa to Southeast Asia to Panama. According to an August 2015 Science Daily article “Venomous Sea Snakes Play Heads or Tails with Predators” there are over 65 species in the ocean and all are highly poisonous. Sea snakes have one of the most toxic venoms known in all snake species. Active predators, the sea snake diet consists mostly of small fish found on coral reefs. Many species spend their entire lives at sea, although they tend to be found in shallow waters.

The Dangerous Saltwater Crocodile

Some say the saltwater crocodile is the animal most likely to eat a human, according to the National Geographic’s “Saltwater Crocodile Profile”. Living around Southeast Asia and the northern coastlines of Australia this marine reptile can reach 23 feet long and 2,200 pounds. It is the largest crocodilian in the world. Although they can swim far out to sea to feast on sharks, their prey mostly includes land-dwelling monkeys, boars, and wild buffalo. They are considered at a low risk for extinction however hunting and habitat loss has put pressure on their populations.

Protecting Marine Reptiles

Humans have put pressure on the populations of many marine reptile species. Hunting, habitat destruction, and pollution are pushing sea turtles and marine iguanas ever closer to extinction. Although the saltwater crocodile is considered safe at the moment the tide may turn if hunting and habitat loss continue. Although reptiles may not be as charismatic as pandas or tigers, they too deserve respect and have a right to exist in their homes.


Will Polio Be Eradicated?

Polio? What is polio? The only time the majority of people in our world encounter that name is when a physician encourages us to have our children immunized against polio. Polio or poliomyelitis is disease caused by a virus called the polio virus. The virus initially infects either the mouth or the intestines then gets into the bloodstream where it is carried to the spinal cord. Once in the spinal cord the virus reproduces causing damage to the nerves. In severe cases of poliomyelitis the patient becomes paralyzed. The polio virus is highly infectious and can be transmitted person-to-person by a fecal-oral route. There are three different types (P1, P2, and P3) of the polio virus that cause poliomyelitis and a person could theoretically have polio three different times since infection with one type of the virus does not protect against infection with the other types of the virus.

A fecal-oral route of transmission is a transmission route in which infected feces (excrement, bowel movement) from one person ends up in the mouth of an uninfected person. Many people do not wash their hands after using the restroom. After changing a diaper some people forget or are distracted and do not wash their hands.

Even though polio is rare today it was at one time a very common disease. Over 13,000 people each year developed the paralyzing form of polio in the United States during the 1940’s. Most of those with paralytic polio were children. Fortunately, even in that time, less than one in 100 people infected with polio developed paralysis. Most (95%) of the people infected with polio did not have any symptoms. Around 4-8% of people infected with polio had flu-like symptoms. Another 1-2% developed an infection of the membranes surrounding the brain (aseptic meningitis). All of those with flu-like symptoms got over the infection with no long-term problems and nearly every one that got aseptic meningitis were fine in 2 to 10 days. The major problems were associated with those that developed paralytic polio. Many people with paralytic polio got better and their muscles started functioning again. However, there were those every year that did not get better and were either paralyzed for life usually on one side or in some cases died. In the temperate regions of the world, summer was a common time to get polio and many parents kept their children at home in hopes of keeping them safe from polio.

It wasn’t until the mid 1950’s that the vaccine developed by Jonas Salk started to drastically reduce the number of polio victims in the world. Another vaccine developed by Albert Sabin (introduced in 1961) continued the decline in

What is a Pelvic Ultrasound? This Diagnostic Test Shows a Broad View of the Pelvis

Much like a transvaginal ultrasound, a pelvic ultrasound is a diagnostic test that gives views of a patient’s uterus, fallopian tubes, ovaries, and the surrounding areas. The difference between the two tests is that a pelvic ultrasound gives a broader, more general view. Often, a pelvic test will be performed first, followed by a transvaginal test. Other times a pelvic ultrasound is all that is necessary.

The preparation for a pelvic ultrasound involves filling the bladder about an hour before test time. Clear liquids (water, tea without milk, clear juices) work best because they produce less gas, an enemy to the ultrasound image.

Reasons for a pelvic ultrasound include:

Pain/ Irregular Bleeding

One of the most common reasons for a pelvic ultrasound is pelvic pain. Many women experience pain from fibroid tumors, ovarian cysts, endometriosis, pelvic infections, and a host of other reasons.

The transducer can capture the image of fibroids, benign uterine tumors. These tumors cause pelvic muscular cramping, especially during menstruation. They can also cause excessive bleeding.

An ovarian cyst, usually uncomplicated (benign), is a result of an egg ripening and not releasing. It can grow to as large as 6 cm or more, causing pain and pelvic pressure. A pelvic ultrasound is often the first test to be done, and if the ovary is not seen clearly, a transvaginal ultrasound might be done to determinine whether it is truly a cyst or a solid mass.

Endometriosis, or the overgrowth of endometrial tissue, can be found in unusual pelvic places, including the regions beyond the ovaries (adnexal), adjacent to the uterus, and even outside of the pelvis. It is thought that the endometrial tissue somehow migrates outside of the uterus through the fallopian tubes instead of being expelled into the vagina during menstruation. A pelvic ultrasound works best for diagnosing endometriosis because it gives a broad view of the areas around the pelvic organs.

Bladder Problems

Although a doctor might specifically order renal (kidney) and bladder ultrasounds for suspected bladder problems, occasionally an anomaly will be seen on a pelvic ultrasound. Because a patient has filled her bladder for this test, it is well-defined and viewable on a pelvic ultrasound. Bladder wall thickening (infections), ureter obstruction(s), and/or possible kidney stones can be detected, clarifying the reason for vague pelvic symptoms.

2nd and 3rd Trimester Pregnancies

Usually termed “obstetrical” ultrasounds, 2nd and 3rd trimester exams are performed in the same way as pelvic ultrasounds. A mother might fill her bladder somewhat less for a second trimester exam, and not at all for a 3rd trimester ultrasound, depending on her comfort level and the technologist’s needs.

This type of pelvic ultrasound shows fetal parts, determines fetal age, can determine fetal sex, and checks for the overall health of the fetus.

For further reference: WebMD

Why Our Food Rots II

This is the second edition of “Why our Food Rots.” To get you up to speed, last week’s article described what causes food to rot: MICROBES! I also mentioned the basic methods of food preservation and that changing the temperature of a food can either slow the growth of microbes or kill them. This week’s article will describe how various chemical treatments help in preserving food. The means of preserving food and the chemicals used to preserve the food are as follows:

  • pickling (salt or sugar; vinegar, a weak acid)
  • salting/sugaring
  • fermentation (alcohol)
  • chemical preservation (lots of compounds too long and hard to pronounce for now)

When people think of chemicals they usually think of compounds with long names that are poisonous to life. That is not really true. We are made up of chemicals. Salt and sugar are chemicals that are commonly found in our bodies. There are other chemicals that are not commonly found in us that can be deadly. Lead is a chemical that you don’t want in your body because it is very poisonous.

Unlike lead, chemicals like salt, and sugar are only poisonous in very very very high concentrations. Salt and sugar are also poisonous to microbes when in high concentrations. High concentrations of salt and sugar actually suck the water out of our cells and out of microorganism’s cells. When water levels get too low in a cell the cell will die because the enzymes in the cell can’t do their work. No enzymes working means no energy being produced. No energy leads to cell death.

There are a lot of examples of people using high concentrations of salt or sugar to preserve food. Beef jerky is one example. The meat is dried and salted to preserve it. Pickles are preserved in a salt brine that prevents the growth of microbes in and on the cucumbers. Vinegar is also used in salt brine to increase the acidity of the brine. Microbes are killed by acidic conditions because acid will also destroy the enzymes that make microbes grow. Jams, jellies and sweet pickles are examples of the use of sugar to preserve food.

These preservation techniques don’t kill us because we can lower the concentration of the salt or sugar by diluting them out with other foods we eat and because of the large mass of our bodies compared to the amount of salt or sugar we eat. Unfortunately for the microbes, their cell body mass is very small and as a result concentrations of salt and sugar that have little effect on us are deadly to them.

Functions and Structure of Ribosomes: Small Organelles that Carry Out the Process of Translation

Ribosomes are small organelles made of RNA and protein that carry out the important work of translating mRNA templates into proteins.

Ribosome Structure – Subunits of RNA and Protein

Ribosomes in eukaryotes are made up of two subunits, a large subunit, called 60-S, and a small subunit, named 40-S. In prokaryotes, the subunits are 50-S and 30-S.

These two subunits are made in the nucleus and join together in the cytoplasm to create the ribosome whenever mRNA is present and proteins need to be made. The two subunits join together, hook onto the mRNA and start protein synthesis. During the production of proteins, the larger subunit binds to tRNA and amino acids and the small subunit binds to the mRNA template. When the ribosome finishes reading the mRNA and making the protein, the two subunits break apart again.

Function of Ribosomes – Protein Construction

The function of ribosomes is to make proteins in a process called protein synthesis. The ribosomes combine amino acids, the building blocks of proteins, in the order specified by a messenger RNA (mRNA) template.

As the ribosome moves along the mRNA and reads the sequence, amino acids are attached to and organized by transfer RNA (tRNA), a special type of RNA that can bind to both the ribosome and amino acids.

Location of Ribosomes in the Cell – Free and Attached Ribosomes

Ribosomes come in two types, free ribosomes and membrane bound ribosomes, which can be found in different places within the cell and carry out slightly different versions of protein synthesis.

Free ribosomes are found floating in the cytosol of the cell, the liquid that fills the cell interior. Free ribosomes can move around in the cytosol and they generally make proteins for use inside the cell.

Membrane bound ribosomes, also called attached ribosomes, attach to the endoplasmic reticulum, creating rough endoplasmic reticulum, RER. These rough ER ribosomes make proteins that will be exported for use outside the cell or used in cell membranes. The proteins generated by ribosomes in the rough ER travel into the ER and are then packaged for transport to the plasma membrane to be incorporated there or sent outside the cell.

Ribosomes are capable of chaning between one type and another. Free ribosomes can become membrane-bound ribosomes and vice-versa depending on what the cell needs at any given time.

It is important for students of biology to understand the function and structure of ribosomes, since these important organelles carry out the steps of protein synthesis that create all of the proteins in the body. Without ribosomes, there would be no protein construction and no work could ever get done inside or out of the cell.

Small Sand Dwellers and Filter Feeders: Eight Unusual Animal Phyla Recognised by Specialists

Large filter feeders (some whales, bivalve molluscs, and barnacles for example) are well known, but the smaller ones are often obscure. Life between grains of sand or mud implies tiny size, which means that these animals are also unfamiliar – rarely seen without the aid of a microscope.

Rotifers, Micrognathozoa, and Gnathostomulids

  • The 100 or so species in the phylum Gnathostomulida are small marine animals. Most are less than 1 mm long, and they scrape food off sand or mud grains, especially in places where there is little oxygen. Gnathostomulid mouthparts suggest that they are related to the rotifers.
  • Micrognathozoa have their own phylum – even though only one species is known so far. Limnognathia maerski was discovered in Greenland in 1994, living in spring water. The animal is minute, less than one tenth of a millimeter long, and therefore one of the smallest known. Very little is known about this phylum, but it is thought to be close to the Rotifera.
  • Rotifers (Phylum Rotifera) are common in fresh water. There are over 2,000 described species of rotifer, and they were discovered early in the dawn of microscopy (by John Harris in 1696). They are able to survive long periods dehydrated, rather like the tardigrades, and this explains how they can get from pond to pond – as bits of ‘dust’ blown in on the wind. Most are less than a millimeter long, and they feed by filtering small particles (fish waste, dead bacteria, algae etc.) at the prodigious rate of 100,000 times their own volume per hour. They are ecologically important for this reason – helping to keep fresh water clean.

(Look at a ‘Gallery of Rotifer Images’).

Gastrotrichs and Kinorhynchs

  • Gastrotrichs are very small and short-lived (most only living for a few days). They typically live between sand grains as part of the ‘meiofauna’. There are about 700 species in this phylum, and it is not at all clear which other phyla are closest to them – body form suggests one set of possibilities, genetic studies another.
  • The 150 or so kinorhynchs, or ‘Mud Dragons’, also live in mud and sand, where they eat diatoms. Like the gastrotrichs it is unclear how this phylum fits in, in the evolutionary sense.

Brachiopods, Bryozoans, and Xenoturbellids

  • Brachiopods are often large animals with two shell valves, much like bivalve molluscs, but they are not closely related to them (or any of the Phylum Mollusca). 99% of all brachiopods are extinct, and those that remain are sessile filter feeders. They usually attach to the substrate by means of a long stalk.
  • Bryozoans (or ectoprocts), with over 8,000 living species, usually built tough calcareous casings for their colonies. This group of small individuals is often called a ‘sea mat’, and it is permanently attached to a rock or large plant. The individuals filter seawater. It is thought that the bryozoans are most closely related to the brachiopods.
  • The phylum Xenoturbellida consists of two known species. They are worm-like and were once thought to be related to the molluscs (because molecular studies indicated the presence of molluscan DNA), but it is now thought that this DNA gets into the animals because they either eat, or parasitise, molluscs. They have a very simple body plan, and very little is known about them.

The animals in seven of these phyla are too small for most people to notice, and the brachiopods (the eighth phylum) will normally be encountered as fossils. As fossils the brachiopods can easily be mistaken for bivalve molluscs.

Getting Electricity from Sewage

Treating human waste is a very expensive problem for most countries. Without treatment, raw sewage can spread disease and kill off the living organisms in our streams and rivers. Contamination of drinking water with sewage is common in countries that do not have the resources to treat their sewage. Sewage treatment is expensive but it does protect our waterways and prevents a lot of human illness. Unfortunately, the need to treat human sewage will never go away as long as people continue to gather together in the cities and towns of our world. About 60 percent of the human waste generated in the U.S. goes to waste treatment plants. Fourteen billion gallons of water are needed each day to carry that waste to the treatment plants. Even so about 10 percent of the waste mentioned above is not treated and goes in the form of raw sewage into our streams and rivers.

There are sewage treatment plants all over the industrialized world that utilize two relatively simple means to treat the sewage. The primary means used to treat sewage is to allow the solid material to settle to the bottom of a sedimentation tank. The sludge that settles to the bottom is pumped into an oxygen-free digester (anaerobic; secondary treatment). There, anaerobic bacteria help to breakdown many of the organic (carbon-containing) compounds in the sludge. The sludge is then allowed to dry and can oftentimes be used a fertilizer.

The liquid on top of the sludge in the sedimentation tank is then pumped to an oxygen (aerobic) containing digester (secondary treatment). The bacteria in the digester then breakdown the organic (carbon-containing) material in the sewage. The biological oxygen demand (BOD) is determined when assessing whether a digester has done its job or not. BOD is the amount of oxygen needed to breakdown the organic material in the sewage. If the sewage were released without this treatment the organisms in the waterways would use up valuable oxygen to breakdown the organic materials killing the fish and other animals dependant on oxygen in the water. By the time treated water is released around 90 percent of the BOD is removed. The water is chlorinated to eliminate most of the bacteria and then the water is released.

All of this takes time and large amounts of electricity to pump the liquids and to aerate (put oxygen in) the sewage. Some researchers from Pennsylvania State University (PSU) have found a very simple way to generate electricity from this sewage and at the same time reduce the BOD by 80 percent. In the Environmental Science and Technology (volume 38, number 7, pages 2281-2285), Hong